What is the sum of X+XX+XXX+XXXX?
08.06.2025 13:55

It’s a matter of interpretation.
What is the sum of X+XX+XXX+XXXX?
as would be assuming that these are representations of conventional numbers, in which case the answer for number bases of five or more would be
1234X
*Note that the abbreviation XL (for XXXX) appeared quite late in the Roman period, and never found universal favour
and for binary would be
What kind of book did you write after turning 55?
11010X
However, X +X^2 +X^3 + X^4 is a valid algebraic answer,
Given the use of upper case, I personally would initially assume Roman numerals*, so the answer would be C (100 in present-day decimal notation)